1. Field of the Invention
The present invention relates to a system for editing a color image displayed with electric signals and, in particular, to a color image system improved in terms of a color adjustment.
2. Description of the Related Art
Related Art 1.
FIG. 25 shows a block diagram of a conventional color correction apparatus disclosed in Unexamined Japanese Patent Publication 4-352569. In FIG. 25, a scanner 60 reads an image. A printer 80 forms the image. A conventional color correction apparatus 7 is composed of the following blocks. A color correction unit 71 performs a color correction. An initial parameter memory 72 stores initial parameters for adjusting an initial color correction level. A data input unit 73 sets up contents of the initial parameter memory 72. A correction parameter memory 74 stores correction parameters for adjusting a color correction level. A fuzzy inference unit 75 infers the correction parameters from operation of a user. An operation unit 76 inputs a direction of the user.
FIG. 26 is a block diagram showing the inside configuration of the color correction unit 71 shown in FIG. 25. In FIG. 26, a color correction table memory 711 stores and corrects a conversion table which corrects data of an input image. A color range detector 712 judges whether or not the color of the image is within a color range to be corrected. A selector 713 selects output depending upon a result of judging of the color range detector 712. A color converter 714 converts a signal of the scanner 60 into a signal of the printer 80. An input level correction unit 715 corrects the level of an input signal. An output level correction unit 716 corrects the level of an output signal.
The operation of the conventional color correction apparatus will now be described. When there is no color correction request of the user, the color correction apparatus 7 is in the color correction state set up by the initial parameters for the color correction. The data input unit 73 calculates initial parameters for the color correction from the color correction level specified in advance and stores the initial parameters in the initial parameter memory 72. The initial parameter memory 72 sets the color correction level calculated by the initial parameter, in the color correction unit 71. The initial parameter memory 72 sets the color correction table H (L, H, S) in the color correction table memory 711 (L stands for lightness, H for hue, S for saturation, hereinafter). The initial parameter memory 72 sets a desired color range Si for the color correction, in the color range detector 712. The initial parameter memory 72 sets various conversion matrixes Mi and functions fi for converting the signal of the scanner 60 to the signal of the printer 80, in the color converter 714.
When the image is input by the scanner 60 in this state, the input signal is provided to the color correction table memory 711, color range detector 712 and the selector 713, in the color correction unit 71. The input signal is decoded to an address using a value of coordinate transformed (L, H, S), and the color correction table memory is read by the decoded address. A signal of the color corrected data is sent to the selector 713.
The color range detector 712 judges whether the input signal is within the desired color range Si for color correction or not. A result of the judging is output to the selector 713. The selector 713 outputs the color corrected signal or the input signal to the color converter 714 depending upon the judging result. The color converter 714 converts the corrected signal or the input signal to a gray scale signal of the printer 80 using the matrix Mi and the function fi, then outputs the converted signal to the printer 80. An image is formed by performing the above procedure to the input signals.
The case of the color correction request of the user being input from the operation unit 76 will now be described. The fuzzy inference unit 75 analyzes and infers the color correction request to obtain color correction parameters, the color correction table H (L, H, S), the desired color range Si for color correction, the conversion matrix Mi and the function fi, then stores the obtained data in the correction parameter memory 74. The correction parameter memory 74 receives the color correction table H (L, H, S), the desired color range Si for color correction, the conversion matrix Mi and the function fi, and sets the received data in the color correction table memory 711, the color range detector 712 and the color converter 714. The image is formed by processing the input signals in the same way as the above.
Related Art 2.
FIGS. 27 to 29 show dialogue boxes in the user guide (pages 158-160) of Photoshop by Adobe Co. (Photoshop is a registered trademark of Adobe Co.).
FIG. 27 shows a dialogue box for adjusting a threshold level for displaying a gray-scale image in black and white. It is possible to set up a border between black and white of the gray-scale image as the threshold level, by moving a mouse pointer right and left with a cursor.
FIG. 28 shows a dialogue box for changing the brightness and contrast. It is possible to change the brightness and contrast by moving the mouse pointer right and left.
FIG. 29 shows a dialogue box for adjusting the brightness and contrast. It is both possible for the dialogue box of FIG. 29 to designate and adjust Red, Green and Blue separately and to adjust Red, Green and Blue together simultaneously as a master mode. The minimum luminance of the image can be adjusted by moving the mouse pointer of shadows. The maximum luminance can be adjusted by moving the mouse pointer of highlights. In addition, the luminance of an intermediate color can be changed by moving the mouse pointer of .gamma. (gamma) without changing the maximum luminance and the minimum luminance.
Histograms are shown on the dialogue boxes of FIGS. 27 and 29. The horizontal axis of the histogram shows brightness value and the vertical axis shows the number of pixels. These histograms are displayed in black and white. The system of Photoshop adjusts an original image directly using the dialogue box. Namely, when a color adjustment of the original image is specified by the dialogue box, the original image itself is adjusted based on the adjustment specification. Since only the adjusted image is displayed, it is impossible to compare the original image and the adjusted image.
Related Art 3.
FIG. 30 shows a procedure of color adjustment shown in pages 249 to 252 of the thesis "Japan Hard Copy" 89 (NIP-30, Kanamori, Kawakami, Odera) entitled "A color adjustment selection of a color image by supplying lattice points in a color space". A dense space 81 is converted to a color space of RGB. The color space of RGB is converted to an L*a*b* space via XYZ color space. Adjustment amount is specified by using the L*a*b* space. After the adjustment, values are reconverted to return to the dense space via the XYZ space and the RGB space.
In a conventional color adjustment, the color space for specifying the color adjustment is sometimes changed from the color space forming an image data so that the color adjustment should match with the human recognition. In this case, the color space of the image data is converted to the color space for specifying the adjustment amount, and then the converted data are inversely converted to the color space of the image data.